Most mechanics are really bad at wiring. I watch them "fix" wires on those TV hotrod shoes, and cringe. (I used to do professional electronic assembly work, and at least I know how to solder properly.)

A popular topic on online car forums is electrical gremlins, almost always from crummy electrical repairs.

Sometimes I see a car where the lights on the rear of the car are wired incorrectly, and I can't understand how this could possibly happen. For example, backup lights (white/clear) are wired the same as the brake lights. The car didn't come out of the factory like that, so at some point someone must have "fixed" it and the result is that some lights come on at the wrong time. I'm amazed someone can look at that and say "yup, my work here is done"

JFYI, those are not necessarily wired incorrectly, car wirings are "queer" a single ground connection (negative/black to frame/body) that has oxidized or however does not make good contact and anything can happen to lights, and tail lights particularly also often suffer from dispersions/bridges in the connectorts due to the effects of humidity/mist[1].

[1] some makes/models are particularly subject to this (FIAT do you hear me?) , and it is very common to need to spray some WD-40 or similar once a year or so on contacts/connectors of tail lights/turn lights.

Could have been an issue with a replacement part. One time I got a replacement headlight that was internally wired backwards from the factory. (High and low beams swapped)

> The repair or modification of wiring harnesses is often a risky repair.

If the repair doesn't make the planes safe according to the regulations they should have been built for, then the planes need to be scrapped.

Safety is achieved by managing risk. Regulations are a derivative description thereof.

If the repair makes the plane meet the letter of the regulations but introduces risks that the regulations didn't consider, you've done a good job at meeting regulations but a bad job at managing actual risk.

The wiring, as it is, is considered unsafe and violates regulation. Boeing is trying to push the false dichotomy between leaving the planes as they are and "fixing" them introducing more risks.

In fact, there is another possibility: that the planes were never airworthy and should have never be flown in the first place and, if they can't be made airworthy, then they should be scrapped.

I am not qualified to judge the relative magnitudes of risk between the cable spacing issue and the rewiring issue. However, it is clear that they each pose some sort of risk.

Although, to play devil's advocate with Boeing's point: if you are to say that those planes are not airworthy because of their cable spacing, then no 737 is airworthy, as the regulation is new.